| After cultivation at 25 °C in 2216E agar medium, two strains of Vibrio gazogenes were isolated from the blood of shrimp affected by epizootic septicemia. The shrimp, Penaeus chinensis, were collected from Xiaying Town, Changyi County, Shandong Province in August 1993. Artificial infections by injection, dipping and feeding methods proved that these isolates were some of the pathogens of the disease. The isolates were tested for more than 50 unit characters and according to Bergey’s Manual of Systematic Bacteriology 9th, were classified as Vibrio gazogenes.
The bacteria were gram negative, curved rods, with single polar flagellum, produced red pigment. Oxidase, arginine dihydrolase, lysine and ornithine decarboxylase tests were negative. Some of the other characteristics, such as production of gas from glucose, utilization of xylose, salicin and sorbitol, negative for nitrates reduced to nitrites, citrate utilization, positive for amylase, gelatinase and lipase production, sensitivity to O / 129, were also proved.
Optimum growth temperature, pH and salinity were 25°C to 30°C, 7.5 to 8.5 and 1.0% to 20% sodium chloride respectively.
These isolates were highly sensitive to Leucomycin, Cefazolin, Novobiocin, Tetracycline, Carbenicillin, Lincomycini and Medemycin. This is the first reported of V. gazogenes as a pathogen of shrimp disease. |
